Every virtual or dedicated server has its own Operating System and functions independently from the servers of other clients. Updating the OS is usually overlooked, but doing that could have lots of benefits for your sites. The most important reason to use the most up-to-date version is that patches are frequently released to repair security holes within the Operating System code, so if you don't install the updates, you risk people with malicious intentions to use these holes and to get access to your content. OS updates are also released for enhanced performance of the system as a whole and for far better compatibility with the hardware available on the market, which can directly impact the efficiency of your websites. If the functionality and the security of your scripts is the reason to update them, you may also discover that their most recent versions require an updated Operating System to be able to function properly, therefore keeping the Operating system up-to-date is always wise.